Astronomers have found a ring of particles surrounding a small, distant space rock at the edge of our Solar System. The ring encircles a strange world called Haumea, a dwarf planet that’s shaped a bit like a squashed egg. Haumea is one of just five officially recognized dwarf planets in the Solar System, but it’s the only one we know of to have its very own ring.
Although Haumea is unique among its peers, this isn’t the first time a ring has been found around a small body like this in our Solar System. In 2014, this same group of astronomers said that they had found two thin rings around a smaller, minor planet called Chariklo that orbits between Jupiter and Neptune. The discovery completely surprised the astronomy community. Up until that point, only the gas giants in our Solar System — Saturn, Jupiter, Neptune, and Uranus — were known to have rings.
But now that rings have been found around another small, distant object, it’s possible that even more bodies far out in our Solar System have rings, too. That poses a puzzle for astronomers: how are these rings forming? Most explanations for ring formation have focused on the biggest planets in our cosmic neighborhood. But now, researchers are going to need to come up with ways to explain how rings are forming around these tiny objects — and how the rings are staying there. “I think that where the rings are coming from, how they’re forming essentially, is going to be a big topic of research,” Amanda Sickafoose, a planetary astronomer at MIT who wrote a Nature editorial on the discovery, tells The Verge.
Astronomers serendipitously found Haumea’s ring, described today in Nature, when they watched the dwarf planet briefly pass in front of a background star, blocking out the star’s light. Such a passing causes a momentary eclipse known as an…